Dodgy Research
by Whenrabbitsattack2-0
Summary: Fionna and Marshall have been dating for a while, but they've never gone all the way. Trouble is, Fionna doesn't even know if they can. After all, her boyfriend is a vampire. How does his body even work, and how can she find out without having to ask? (My explanation for the phenomena of vampire boners. T for obvious reasons.)


' Baby, what are we even doing here?' Cake whined as Fionna led her between row after row of dusty bookshelves. The archival library was crammed with tomes that nobody had browsed for eons, or so it seemed.  
' I told you Cake, I need to find this stuff out.'  
' But honey, I've already told you all you need to know.' Fionna shook her head, running her fingers across the spines of several books, her lips tracing the title of each one as her hand brushed past.  
' But what if it's different for vampires, Cake? I mean I guess it'll be... essentially the same, but it's not like we're you and Lord. He might not even have the same.. parts.' She mumbled, blushing slightly. Cake sighed and waved a paw helplessly.  
' Fine, I can see what you mean. But why do I have to be here?' Fionna thought it over for a second.  
' Um.. I guess you don't really need to be? If you wanna go do something else then that's cool.' Cake nodded and started trekking back the way they had come.  
' I don't really like libraries. I'll see you later, okay doll?' Fionna grunted non-committally in response, once again paying attention to the books.

She crossed down a few more shelves, then wrapped her fingers around a book triumphantly, heaving it out onto the ground.  
' Aha! Vampyres, The comprehensive guide to the creatures of the night.' She read out loud, picking up the heavy book and moving it over to a table. She flipped open to the contents page.

_Origins...5_  
_Habitat... 26_  
_Nutrition...45_  
_Biology...62_  
_Reproduction...85_  
_Culture...92_  
_Psychoanalysis...112_

She flipped through the pages until she reached the heading she wanted, then turned up the gas lamp sitting next to her and settled in to read.

_The reproduction of vampires is rather elemental in nature, considering that they are a species created from their prey. Obviously, the easiest form of reproduction unique to vampires is their ability to parasitically convert their victims into one of their own kind through their venom. However, seeing as this is not the natural reproductive state of their origin species, vampires are also capable of reproduction through parenthood, though perhaps not so much in the typical fashion. In this chapter, I shall first discuss the parasitic form of reproduction, then the secondary genetic reproductive capability._

Yawn. This sounded boring. But at least she didn't need to read all the parasitic junk, right? If you get bit and you don't die, then you turn into one of them. Simple. She flipped through the chapter until she caught a glimpse of a secondary heading, then turned back a few pages.

_Genetic reproduction_  
_ Although the primary way for the vampire species as a whole to dominate is through parasitic reproduction, they are also capable of genetic reproduction to some extent. However, this method is neither efficient nor easy to execute, so true 'vampire children' as it were, are extraordinarily rare._

_The females of the vampiric species are unable to bear children. Because the basis of vampire biology, as previously discussed, is through the tissues of the body being sustained by the blood they ingest, Vampires are classed as undead. Although, as stipulated, they do still breathe, they have no heartbeat and blood permeates, rather than delivers to the tissues._  
_Thus, as their bodies, and their previously human reproductive systems are dead, Vampire females cannot concieve. And even if they could, the quantities of food they would need to ingest in order to sustain not only their own tissues but that of the growing fetus would be so monumental that it would be nigh on impossible, even in the rare mutation Carnelian Chromius._

_However, although the females are biological dead-ends, the males of the species are not. Although once dead, the testicles stop creating sperm due to that no longer being the primary way to reproduce, those that are left are still viable. This means that if a vampire male were to have a sexually compatible female partner with a working reproductive system, he would technically be able to father a child as long as all of the remaining viable sperm had not already been ejaculated._

_There have been few rare recorded cases of vampires both male and female, who still had fully functioning secondary reproductive systems. In 90% of these cases, they were also shown to have remarkably weak or impotent venom, suggesting that the energy that would normally have gone into manufacturing and storing the venom was instead directed to maintaining the already existing reproductive system. It is also interesting to note that this modification is slightly more common in the rarer mutation of Carnelian Chromius, the colour-eating vampires, giving rise to the possibility that they may soon be a species all of their own. _  
_It is this minority that may have possibly been to blame for the popular human myth of the succubus, an evil demon that hypnotized vulnerable men and women and had sex with them, supposedly in an attempt to kill them. _  
_While it is possible some of these tales may have been more fact than fiction, as vampires are as capable of reaching orgasm as their host species is, the general consensus is that a petty few gave rise to a legend that would allow adulterous men and women to keep their noses clean for centuries._

_Vampires, similarly to their origin species, are known to engage in intercourse for pleasure, as opposed to reproductive purposes. Concerning the biology of the obsolete sexual organs, I have already explained the subject on page 74, and do not intend to repeat myself._

_Vampire children are-_

Fionna stopped reading right there and leant back in her chair, huffing a huge sigh that blew up her fringe. So Cake was right. He could get her pregnant. Unless he had already-  
She stopped the thought in its tracks, putting her head in her hands as she blushed a deep crimson. That was not something she was going to think about.  
And besides, Marshall drank shades of red, so didn't that technically make him a- a Carnelian Chromius or whatever? So there was a chance that all of his... erm, equipment was still working.  
But she still didn't know if sex between them would be exactly the same as it would be if he was still human. While Cake was explaining the birds and the bees to her, she had managed to find a very, very old textbook detailing human biology. And Marshall had once been human. But still, she couldn't assume it would be exactly the same.  
With that logic in her mind, she flipped to page 74 and gasped, quickly clapping a hand over her mouth as she did so.

On page 74, a large block of text. On page 75, a detailed sketch of a naked male vampire. With a erection. Fionna stared at the drawing for a few moments, completely shocked. What the hell?

_ Vampiric males are still entirely capable of gaining and sustaining an erection, (fig. 1) although the consequences of such are slightly different than the equivalent situation in a human male. Due to the fact that blood (Or in the case of mutation, the colour red and sometimes even green) is the primary source of nutrition, having such a large quantity drained down into the penis has quite far-reaching effects._

_Normally, once ingested, blood simply permeates every tissue in the body, becoming a source of energy for the slightly altered cells rather than the gateway for it. However, when sexually aroused,the cavernous spaces of the penis become filled with blood as they would in a human. But due to the fact that this blood must have come from somewhere, where they previously would have been providing energy, it is common for male vampires experiencing sexual arousal to report some loss of feeling in their extremities, starting with fingers and feet and sometimes moving up to whole hands and ankles. During the very energetically demanding process of copulation, almost all reserves of blood will be used up, and the remaining amount stored within the shaft of the penis will flow back once intercourse, orgasm and ejaculation have been completed. This blood will then sustain the individual for a short time before he is able to feed again._

_But, as some may have contrived from my explanation, If our hypothetical male is sexually stimulated when there is not enough blood reserves to power the body as well as grow and maintain an erection, he will be incapable of full arousal. And immediately after coitus,the male in question will be famished, as his reserves of blood will be running extremeley low due to the amount used up in the process of fornication._

_in summary, the male vampire is as capable of maintaining an erection and orgasming as his host species, but will be unable to do so when hungry and will need to feed directly after sex._

_Female vampires (fig. 2 pg 77) can engage in intercourse and orgasm like their host species, but the process is not nearly as draining for them as it is for their male counterparts, as they have no need to redirect such large amounts of the blood in their bodies. For them, it is no different than a bout of strenuous aerobic exercise, and their loss of blood and subsequent need to feed are similar accordingly._

Fionna re-read the paragraph once again, just to make sure she understood. When she had finished she pushed her bunny hat further up her forehead and frowned, leaning against her hand.  
So basically.. Marshall-lee was just like a normal dude except he couldn't get it up when he was hungry?  
Wow, vampires were a weird species.  
As she closed the book and turned it over in her hand, she realised how odd it was that someone had done such extensive research on them. This book could only have been written by a vampire, or something close to them, like a demon maybe.

' Fionna? Fionna are you here?' Fionna fumbled with the book and draped herself over it as best as she could, panicking at the sound of that voice.  
' Uh... Yeah, I'm here.' she called quietly back, wary of Turtle Princess coming over and telling her off for talking. Marshall-lee floated around one of the bookshelves, glancing around until he spotted her, at which point he smiled.  
' I thought Cake was lying when she said you were here... What's up, baby?' He drifted over and gave her a kiss on the cheek, Fionna giggling nervously as he slung an arm across her shoulders.  
' Um, nothing much.. I just had to read about something.'  
' Something you wanna tell me, Fi?' He said, recognising the tone of her voice. Fionna swallowed and leaned back off of the book. As Marshall-lee read the title, his eyebrows went way up and he glanced over at Fionna, a slightly confused half-smile on his lips.  
' You know anything you wanted to know I could've told you right? Lemme see that.' He took the book from her and started flipping through the pages, Fionna blushing steadily deeper as he became closer and closer to the back of the book.  
In the last third, he flipped a page then did a double take and turned it back over, raising an eyebrow at what he saw. Fionna knew exactly which page he was on.

' By any chance, Bunny... you weren't reading up on whether we were compatible... physically, were you?' Fionna turned crimson and nodded, refusing to meet his eye. At the sound of his musical laugh, she looked up and he picked her face up in his hands and kissed her once, gently.  
' Fionna, you don't need to know how I work to figure out that we go together, okay? We just gotta try and see.' At this, he leaned in and kissed her again, Fionna mildly surprised when he opened his mouth and slid his tongue between her lips. After a few minutes, Marshall-lee broke away and she gasped for air, only to subside into a series of small, high pitched moans as he sucked and licked on her neck, his hand slowly traveling up her thigh. When she felt his fingertips edge beneath the hem of her skirt, she stopped him and looked at him skeptically, breathing hard.  
' When you said... we just gotta try... and see, I didn't... think you meant... right now.' She panted. Marshall-lee smiled at her suggestively, stripping off his jacket in one swift movement.  
' Why not right now? It's night time, there's practically no-one here.'  
' Yes there is, Turtle Princess!' Marshall-lee shrugged, pulling off his shirt, and Fionna admired his physique for a few moments before remembering she wasn't supposed to be condoning this.  
' Babe, she's on the other side of the library, curled up in her shell with a yaoi manga. We could do whatever we wanted and she wouldn't notice a thing, which is exactly what I intend to do.' With that he advanced on her again, and Fionna was powerless to try and stop him.  
' Marshall, I really don't think- U-uhh... I mean, I really- ah-ahhh!... Ah, M-Marshall!'

* * *

'Hey, Marshall?'  
' Damn, I'm starving. Yeah, sweetheart?'  
'...What's a yaoi manga?'

END

**Author's note: In various places around the internet, a lot of the lemony fanfics have been made somewhat obsolete by people coming in and discrediting them by (entirely fairly) pointing out that vampires can't get erections because they have no blood supply. So basically, this is my explanation as to how vampire's bodies work, and this is how Marshall's body works in all of my fanfiction.** **Do you have your own little headcanon on the engaging subject of vampire boners? Leave a review and let me know ;D**

-WRA


End file.
